Taxonomy

Citation: Beella Banner & Blow, 1960Rank: genusType species: Globigerina digitataTaxonomic discussion: Beella differs from Bolliella in possessing a trochospiral test and an umbilical aperture in the adult. Young individuals of Beella have an extraumbilical aperture. The height of the spire varies considerably but becomes increasingly high spired in adults, with a tendency toward streptospiral.coiling. This suggests an affinity with Hastigerinella rhumbleri Galloway, but Beella differs by lacking multiple hornlike chamber extensions and advanced streptospiral coiling. In general, the surface ultrastructure of Beella is similar to but much finer than that of Globigerina (Gg.) bulloides (Srinivasan and Kennett, 1975). Although Parker (1962) noted its close affinity with Globigerina, she suggested that Beella may well be referred to Hastigerinella. Lipps (1966) considered Beella as a synonym of Globigerina. Banner and Blow (1960) regarded Beella as a subgenus of Globorotalia, but later Blow (1969) considered it as a subgenus of Globigerina. We agree with Loeblich and Tappan (1964) that Beella is more closely related to Globigerina, but its radially elongate chambers, relatively finer surface ultrastructure, and a restricted stratigraphic occurrence justify generic rank to Beella. [Kennett & Srinivasan 1983]

NB These concise distinguishing features statements are used in the tables of daughter-taxa to act as quick summaries of the differences between e.g. species of one genus.They are being edited as the site is developed and comments on them are especially welcome.

Description

Diagnostic characters: Species assigned to Beella have a small trochospiral test similar to Globigerina but commonly with strongly convex spiral side, chambers globular becoming ovate or radially elongate. The test surface is characterized by a fine, irregular pattern of raised ridges (spine bases) surrounding the pores. [Kennett & Srinivasan 1983]

Biogeography and Palaeobiology

Phylogenetic relations: The genus Beella evolved from Globigerina (Gg.) bulloides in the late Miocene and includes two species: B. praedigitata (Parker) and B. digitata (Brady) [Kennett & Srinivasan 1983]

Biostratigraphic distribution

Geological Range: Last occurrence (top): Extant Data source: Total of range of species in this databaseFirst occurrence (base): in upper part of Tortonian Stage (70% up, 8.6Ma, in Tortonian stage). Data source: Total of range of species in this database